Power Module with Press-Fit Contacts

ABSTRACT

A method of forming a semiconductor device includes providing a substrate that comprises a metal region, forming an encapsulant body of electrically insulating material on an upper surface of the metal region, forming an opening in the encapsulant body, and inserting a press-fit connector into the opening, wherein after inserting the press-fit connector into the opening, the press-fit connector is securely retained to the substrate and an interfacing end of the press-fit connector is electrically accessible.

BACKGROUND

Many applications such as automotive and industrial applications utilizepower semiconductor devices such as IGBTs (insulated gate bipolartransistors), power MOSFETs (metal oxide semiconductor field effecttransistors), power diodes, etc. These devices arranged in a powerconverter circuit such as single and multi-phase half-wave rectifiers,single and multi-phase full-wave rectifiers, voltage regulators, etc.Integrated power modules (IPMs) can include power semiconductor devicesthat form a power converter circuit and the logic controls the switchingof the power semiconductor devices. IPMs can include a multi-layer powerelectronic substrate such as a DBC (direct bonded copper), IMS(insulated substrate) or AMB (active metal brazed) substrate and aplastic housing that encloses the multi-layer power electronicsubstrate. While offering advantageous performance characteristics,features of IPMs such as the power electronics substrate and the plastichousing make IPMs cost prohibitive in certain applications.

It would be desirable to produce a produce a semiconductor power moduleat lower cost with similar or better performance characteristics thanconventional solutions.

SUMMARY

A method of forming a semiconductor device is disclosed. According to anembodiment, the method comprises providing a substrate that comprises ametal region, forming an encapsulant body of electrically insulatingmaterial on an upper surface of the metal region, forming an opening inthe encapsulant body, and inserting a press-fit connector into theopening, wherein after inserting the press-fit connector into theopening, the press-fit connector is securely retained to the substrateand an interfacing end of the press-fit connector is electricallyaccessible.

Separately or in combination, the encapsulant body is formed by amolding process whereby liquified mold material is formed on thesubstrate and subsequently hardened, wherein forming the openingcomprises arranging a fixed pin over the substrate prior to the moldingprocess, and wherein the fixed pin prevents the liquified mold materialfrom forming at a location corresponding to the opening.

Separately or in combination, the method further comprises forming arecess in the upper surface of the metal region, wherein the opening isformed directly over the recess, and wherein the opening is larger thanthe recess such that the recess is completely exposed by the opening.

Separately or in combination, the recess has a first diameter at theupper surface of the metal region, and a diameter of the opening at alower surface of the encapsulant body that interfaces with the uppersurface of the metal region is greater than the first diameter.

Separately or in combination, the opening is tapered such that diameterof the opening gradually increases moving away from the lower surface ofthe encapsulant body.

Separately or in combination, the recess is formed before forming theencapsulant body.

Separately or in combination, the recess is formed after forming theencapsulant body.

Separately or in combination, the recess extends completely through themetal region, and the recess is formed by drilling the upper surface ofthe metal region and by drilling a rear surface of the metal region thatis opposite from the upper surface of the metal region.

Separately or in combination, inserting the press-fit connector into theopening comprises inserting the press-fit connector into the recess, andwherein the press-fit connector is securely retained to the substrate bycompressive force applied by the substrate to a base portion of thepress-fit connector.

Separately or in combination, the base portion of the press-fitconnector has a higher material hardness than the metal region.

Separately or in combination, the method further comprises arranging areceptacle in the opening and attaching the receptacle to the substrate,inserting the press-fit connector into the opening comprises insertingthe press-fit connector into the receptacle, and after inserting thepress-fit connector into the opening the press-fit connector is securelyretained to the substrate via the receptacle.

Separately or in combination, the substrate is an entirely metalstructure.

Separately or in combination, the substrate is a power electronicssubstrate that comprises an electrically insulating substrate and astructured metallization layer disposed thereon, and wherein the metalregion is a portion of the structured metallization layer.

A semiconductor device is disclosed. According to an embodiment, thesemiconductor device comprises a substrate that comprises a metalregion, an encapsulant body of electrically insulating material on anupper surface of the metal region, an opening in the encapsulant body,and a press-fit connector arranged in the opening and securely retainedto the substrate such that an interfacing end of the press-fit connectoris electrically accessible.

Separately or in combination, the semiconductor device further comprisesa recess in the upper surface of the metal region, and the opening isdirectly over the opening and is larger than the recess such that therecess is completely exposed by the opening.

Separately or in combination, the press-fit connector is securelyretained to the substrate by compressive force applied by the substrateto a base portion of the press-fit connector.

Separately or in combination, the press-fit connector comprises K88copper alloy, and the metal region comprises a metal with a lowermaterial hardness than K88 copper alloy.

Separately or in combination, the semiconductor device further comprisesone or more power semiconductor devices mounted on the substrate andencapsulated by the molded body, and the press-fit connector provides apoint of electrical contact to a terminal of the one or more powersemiconductor devices via the metal region.

Separately or in combination, the semiconductor device is a powersemiconductor module that comprises a power converter circuit.

Separately or in combination, the substrate is arranged between twoprinted circuit boards, and wherein the semiconductor device comprisesone of the press-fit connectors extending into each of the two printedcircuit boards.

Those skilled in the art will recognize additional features andadvantages upon reading the following detailed description, and uponviewing the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

The elements of the drawings are not necessarily to scale relative toeach other. Like reference numerals designate corresponding similarparts. The features of the various illustrated embodiments can becombined unless they exclude each other. Embodiments are depicted in thedrawings and are detailed in the description which follows.

FIG. 1 illustrates from a cross-sectional perspective providing a metalregion with an encapsulant body on an upper surface of the metal region,according to an embodiment.

FIG. 2 , which includes FIGS. 2A and 2B, illustrates from across-sectional perspective openings formed in the encapsulant body,according to embodiments. FIG. 2A illustrates a geometry of the openingsaccording to one embodiment, and FIG. 2B illustrates a geometry of theopenings according to another embodiment.

FIG. 3 , which includes FIGS. 3A and 3B, illustrates from across-sectional perspective a technique for forming the openings in theencapsulant body, according to an embodiment. FIG. 3A illustrates thetechnique used to form openings with one geometry, and FIG. 3Billustrates the technique used to form openings with another geometry.

FIG. 4 , which includes FIGS. 4A and 4B, illustrates from across-sectional perspective recesses formed in the metal regionunderneath the openings, according to embodiments. FIG. 4A illustrates ageometry of the recesses according to one embodiment, and FIG. 4Billustrates a geometry of the recesses according to another embodiment.

FIG. 5 , which includes FIGS. 5A and 5B, illustrates from a plan-viewperspective geometries of the openings and the recesses, according toembodiments. FIG. 5A illustrates a plan-view geometry of the openingsand the recesses according to one embodiment, and FIG. 5B illustrates aplan-view geometry of the openings and the recesses according to oneembodiment.

FIG. 6 , which includes FIGS. 6A and 6B, illustrates from across-sectional perspective a technique for forming the openings in anencapsulant body over recesses formed in a substrate, according to anembodiment. FIG. 6A illustrates the technique used to form openings withone geometry, and FIG. 6B illustrates the technique used to formopenings with another geometry.

FIG. 7 , which includes FIGS. 7A, 7B and 7C, illustrates from across-sectional perspective inserting press-fit connectors into theopenings and the recesses, according to embodiments. FIG. 7A illustratesan arrangement of the press-fit connectors in the recesses in a firstembodiment, FIG. 7B illustrates an arrangement of the press-fitconnectors in the recesses in a second embodiment, and FIG. 7Cillustrates an arrangement of the press-fit connectors in the recessesin a third embodiment.

FIG. 8 illustrates from a cross-sectional perspective technique forsecuring the press-fit connectors with receptacles that are disposedwithin the openings, according to an embodiment.

FIG. 9 , which includes FIGS. 9A and 9B, illustrates from an isometricview a power semiconductor module comprising press-fit connectorssecured to a lead frame. FIG. 9A illustrates the power semiconductormodule with the internal features being visible, and FIG. 9B illustratesthe exterior of the power semiconductor module.

FIG. 10 illustrates from a cross-sectional perspective a powersemiconductor module comprising press-fit connectors secured to a powerelectronics substrate.

FIG. 11 illustrates from a cross-sectional perspective a semiconductorpackage comprising press-fit connectors secured to a metal clip.

FIG. 12 illustrates from a cross-sectional perspective an assemblycomprising two printed circuit boards and a substrate with press-fitconnectors sandwiched in between the two printed circuit boards.

DETAILED DESCRIPTION

Embodiments of a semiconductor device comprising press-fit connectorsand corresponding methods for forming a semiconductor device comprisingpress-fit connectors are described herein. The semiconductor device mayinclude a substrate, an encapsulant body, and one or more semiconductordies that are encapsulated by the encapsulant body. The press-fitconnectors are securely retained to a metal region of the substrate andform an electrical connection with a terminal of the semiconductor diesvia the substrate. The press-fit connectors may protrude out from a mainface of the encapsulant body, thereby enabling a press-fit connectionbetween the semiconductor device and a receiving apparatus, such as aPCB. Advantageous techniques are described herein for providing thesubstrate and securing the press-fit connectors to the substrate. In oneembodiment, a recess is formed in the metal region of the substrate, andthe press-fit connectors are securely retained by compressive forceapplied between the metal region and the press-fit connectors. Becausethe substrate can be formed using low-cost metal processing techniquesand the press-fit connectors can be reliably secured to the substrateusing the techniques described herein, a semiconductor device such as apower semiconductor module with advantageous performance can be formedat lower cost than current solutions.

Referring to FIG. 1 , a method of forming a semiconductor devicecomprises providing a substrate 100 that comprises a metal region 102.Generally speaking, the substrate 100 can be any carrier structure orelectronics element with sufficient mechanical strength to accommodatethe press-fit connector described herein. According to an embodiment,the substrate 100 is a completely metal structure. Examples of thesestructures include lead frame structures, e.g., a die pad or landingpad, and metal interconnect clips. According to another embodiment, thesubstrate 100 is a multi-layer electronics carrier. Examples of thesestructures include power electronics carriers, e.g., DCB substrates, AMBsubstrates, IMS substrates and PCBs. In that case, the metal region 102can be a structured metallization layer that is disposed on an uppersurface of an insulating region (not shown in FIG. 1 ). The metal region102 can comprise or be plated with Cu, Ni, Ag, Au, Pd, Pt, NiV, NiP,NiNiP, NiP/Pd, Ni/Au, NiP/Pd/Au, or NiP/Pd/AuAg, for example. Generallyspeaking, the metal region 102 can have a thickness as measured betweenan upper surface 104 and a lower surface 106 in the range of 0.5 mmthick and 10 mm thick. In one particular embodiment, the metal region102 has a thickness is in the range of 1.0 mm thick and 2.0 mm thick.

An encapsulant body 108 of electrically insulating material is formed onthe upper surface 104 of the metal region 102. According to anembodiment, the encapsulant body 108 is formed by a molding techniquewhereby the substrate 100 is placed in a three-dimensional chamber andliquified encapsulant material, e.g., a thermosetting plastic, isinjected into the into the chamber. Examples of these techniques includeinjection molding, transfer molding, and compression molding. Accordingto another embodiment, the encapsulant body 108 is formed by alamination technique whereby multiple layers of laminate material, e.g.,woven glass fiber, FR-4, etc., are successively stacked on top of oneanother.

Referring to FIG. 2 , openings 110 are formed in the encapsulant body108. The openings 110 are formed to reach the upper surface 104 of thesubstrate 100. Generally speaking, the openings 110 can be formedaccording to any of a wide variety of techniques such as drilling,etching, etc. The openings 110 shown in FIG. 2A are tapered such that adiameter of the opening 110 increases moving away from the upper surface104 of the metal region 102. The openings 110 shown in FIG. 2B have asubstantially uniform diameter throughout a complete depth of theopening 110. More generally, the openings 110 can have a wide variety ofgeometries, and may be tailored to accommodate a particular press-fitconnector geometry.

Referring to FIG. 3 , a technique for forming the openings 110 is shown.According to this technique, the encapsulant body 108 is formed by amolding process whereby liquified mold material is formed on thesubstrate 100 and subsequently hardened. Before performing the moldingprocess, a fixed pin 112 is arranged over the substrate 100. The fixedpin 112 has a geometry corresponding to the desired geometry of theopening. The fixed pin 112 prevents the liquified mold material fromforming at a location corresponding to the opening 100. That is, thefixed pin 112 is used to displace the liquified material, therebycreating a void in the encapsulant body 108. Alternatively, the openings110 may be formed by initially the encapsulant body 108 to cover thesubstrate 100 and subsequently removing encapsulant material, e.g. byetching, drilling, etc.

Referring to FIG. 4 , after forming the encapsulant body 108 and formingthe openings 110, a recess 114 is formed in the upper surface 104 of thesubstrate 100. The recess 114 is formed in a portion of the substrate100 that is exposed by the openings 110. The recess 114 can be formed byany of a variety of metal processing techniques, e.g., drilling,etching, punching, etc. According to an embodiment, the recess 114 isformed by a mechanical drilling technique whereby a drill bit penetratesthe metal region 102. According to another embodiment, the recess 114 isformed by a laser drilling technique whereby highly concentrated energyis directed at the upper surface 104 of the metal region 102. As shownin FIG. 4A, the recess 114 can be formed to partially penetrate themetal region 102 such that a thickness of metal remains beneath therecess 114. As shown in FIG. 4B, the recess 114 can be formed so as tocompletely extend between the upper surface 104 and the lower surface106 of the metal region 102. In this case, the recess 114 can be formedby drilling the upper surface 104 of the metal region 102 and bydrilling the rear surface 106 of the metal region 102. As shown, therecess 114 can have a substantially uniform diameter throughout a depthof the recess 114. Alternatively, the recess 114 can have a variety ofdifferent geometries such as a tapered geometry wherein a width of therecess 114 decreases moving away from the upper surface 104.

According to an embodiment, the opening 114 is formed to be larger thanthe recess 114. In particular, the recess 114 may have a first diameterD1 that is measured at the upper surface 104 of the metal region 102,and a diameter of the opening 110 at a lower surface of the encapsulantbody 108 that interfaces with the upper surface 104 of the metal region102 is greater than the first diameter D1. That is, the opening 114 iswider than the recess at a location wherein the two features interfacewith one another. According to an embodiment, the first diameter D1 canbe in the range of 1 mm-3 mm, and the diameter of the opening 110 at alower surface of the encapsulant body 108 can be in the range of 1.10mm-3.5 mm. In a particular embodiment, the first diameter D1 can beabout 2 mm while the diameter of the opening 110 at the lower surface ofthe encapsulant body 108 can be about 2.1 mm to 2.25 mm. In relationalterms, the diameter of the opening at the lower surface 106 can be about5% to 25% larger than the first diameter D1.

Referring to FIG. 5 , various plan-view geometries of the openings 110and recesses 114 are shown. In each of these examples, the opening 110is formed directly over the recess 114 and is larger than the recess 114such that the recess 114 is completely exposed by the opening 110. As aresult, a portion of the upper surface 104 that completely surrounds therecess 114 is exposed by the opening 110. In this way, the recess 114 iscompletely exposed and a small lateral margin is provided to ensure thatthe recess 114 is completely accessible for the insertion of press-fitconnectors, e.g., in a manner to be described in further detail below.Moreover, as illustrated, the openings 110 may have different geometriesfrom a plan-view perspective. These geometries can be combined with anyof the recess 114 geometries described herein.

Referring to FIG. 6 , an alternate technique for forming the recesses114 and the openings 110 in shown. According to this technique, therecesses 114 are formed before forming the encapsulant body 108. Therecesses 114 can be formed according to any of the previously describedtechniques. In this case, the fixed pins 112 are arranged over therecesses 114 before the encapsulation process and prevent the moldmaterial from forming over the recesses 114 in a similar manner aspreviously described. Any of the previously described geometries and/orarrangements of the openings 110 and recesses 114 may be obtained bythis technique.

Referring to FIG. 7 , press-fit connectors 116 are provided. Thepress-fit connectors 116 are electrically conductive structures. Forexample, the press-fit connectors 116 may include a core of electricallyconductive metal e.g., Cu, Al, etc., with an anticorrosion plating,e.g., Ni, Ag, Au, etc. disposed outside of the core. The press-fitconnectors 116 are inserted into the openings 110 such that a baseportion 118 of the press-fit connectors 116 is disposed within therecess 114. The larger size of the openings 110 relative to the recesses114 and/or the tapered geometry of the openings 110 may aid in guidingthe press-fit connectors 116 into the recesses 114 during the insertionprocess. Moreover, as shown, the base portion 118 of the press-fitconnectors 116 may comprise a pointed or tapered end that further aidsin guiding the press-fit connectors 116 into the recesses 114 during theinsertion process. Once inserted into the recesses 114, the press-fitconnector 116 is securely retained to the substrate 100 and aninterfacing end of the press-fit connector 116 is electricallyaccessible. In this arrangement, the press-fit connectors 116 can bemated with a circuit interface, such as a printed circuit board, byinserting the interfacing ends of the press-fit connectors 116 intocorrespondingly shaped receptacles in the circuit interface. Thegeometry of the press-fit connectors 116 and the receptacles to whichthey interface with may be such that a force fitting connection existsbetween the two. To this end, the press-fit connectors 116 may compriseretention features 120 at or near the interfacing ends to aid in thisforce-fitting connection. The interfacing ends may of the press-fitconnectors 116 may be designed to plastically deform and/or may includea spring-loaded contact mechanism to enhance I/O connectivity. Apartfrom the retention features, the press-fit connectors 116 may comprise acylindrical core with a diameter in the range of 0.5 mm-3 mm.

According to an embodiment, the press-fit connectors 116 are retained tothe substrate 100 by compressive force applied by the substrate 100 tothe base portion 118 of the press-fit connector 116. That is, thedimensions of the recess 114 and the base portion 118 of the press-fitconnector 116 are such that pressure is applied to the press-fitconnector 116 after insertion into the recess 114. Generally speaking,this compressive force arrangement can be made possible by anarrangement whereby the base portion 118 of the press-fit connector 116has a complementary geometry as the recess 114 and whereby the recess114 is slightly smaller than the base portion 118 of the press-fitconnector 116. For example, a minimum diameter of the recess 114 betweentwo opposite sidewalls of the recess 114, e.g., the first diameter D1 inthe case of a uniform width recess 114, can be between about 2% to 15%less than a maximum diameter of the base portion 118 of the press-fitconnector 116 that is disposed within the recess 114. Stated innumerical terms, the minimum diameter of the recess 114 can be in therange of 0.5 mm-2.5 mm, whereas the maximum diameter of the base portion118 of the press-fit connector 116 can be in the range of 0.425 mm-2.45mm. In particular embodiment, the minimum diameter of the recess 114 is2.0 mm and the maximum diameter of the base portion 118 is about 2.1 mm.

The material properties of the substrate 100 and the press-fitconnectors 116 may be selected to enhance the compressive force appliedby the substrate 100 to the base portion 118 press-fit connector 116and/or to ensure that a stable mechanical connection exists between thetwo elements. In particular, the material of the press-fit connectors116 may be relatively harder than the material of the substrate 100. Inthis context, material hardness may be measured on the Vickers scale(Hv). By selecting the material of the press-fit connector 116 to berelatively harder than the material of the substrate 100 that appliespressure to the press-fit connector 116, this ensures that more plasticdeformation occurs in the substrate 100 than in the press-fit connector116. In one example, the portion of the substrate 100 that appliescompressive force on the press-fit connectors 116 comprises pure orsubstantially pure copper, and the press-fit connectors 116 comprises acopper alloy that is harder than pure or substantially pure copper,e.g., K88 alloy copper.

The press-fit connectors 116 may be secured to the power module byexclusively mechanical force. That is, no adhesive bonds or welded bondsmay be provided between the press-fit connectors 116 and the substrate100. Alternatively, a conductive adhesive, e.g., solder, sinter, glue,etc., may be provided between the press-fit connectors 116 and thesubstrate 100 so as to provide further mechanical retention. In additionto the compressive force applied by the substrate 100, the encapsulantbody 108 may additionally provide a degree or mechanical pressure and/ormechanical retention of the press-fit connectors 116.

Referring to FIGS. 7B and 7C, optional arrangements of the press-fitconnectors 116 are shown. In the embodiment shown in FIG. 7B, thepress-fit connectors 116 are arranged to extend away from the substrate100 in opposite directions. This configuration allows for electricalconnectivity on two different sides of the assembly. While the depictedembodiment shows one of the openings 110 in the encapsulant body 108disposed over the press-fit connector 116 that extends out from the rearsurface of the substrate 100, in other embodiments this opening may beomitted. In the embodiment shown in FIG. 7C, the press-fit connectors116 comprise a widened section 120 above the base portion 118 that isinserted in the recess 114. The widened section 120 may have a diametercorresponding to the diameter of the opening, e.g., within 100% and 105%of the diameter of the opening, so that a form-fitting connectionexists. In this way, additional mechanical stabilization for thepress-fit connector 116 is provided.

Referring to FIG. 8 , an alternate technique for securely retaining thepress-fit connector 116 to the substrate 100 is shown. According to thistechnique, after forming the openings 110, a receptacle 122 is arrangedin the openings 110 and attached to the substrate 100. The receptacle122 can be a tubular structure of metal or plastic (e.g., conductiveplastic) that is dimensioned to receive the press-fit connectors 116.The receptacle 122 can be secured to the substrate 100 using aconductive adhesive 124, e.g., solder, sinter, conductive glue, etc.After securing the receptacle 122 to the substrate 100, the press-fitconnectors 116 can be inserted into the receptacles 122 and securelyretained thereafter. The receptacles 122 can be dimensioned and have amaterial composition so as to apply compressive force to the press-fitconnector 116 in a similar manner as previously described with respectto the recesses 114 and the press-fit connector 116. Separately or incombination, a further conductive adhesive 124 may be provided withinthe receptacle 122 to provide an electrical and mechanical connection.

Referring to FIG. 9 , a semiconductor power module 200 with press-fitconnectors 116 is depicted, according to an embodiment. Thesemiconductor power module 200 comprises a metal lead frame 202 with aplurality of die pads 204 and landing pads 206 that are spaced apartfrom the die pads 204. The metal lead frame 202 can be provided from arelatively uniform thickness piece of conductive metal with a generallyplanar upper and lower surfaces, and the features of the substrate 100(e.g., the die pads 204 and landing pads 206) are formed by metalprocessing techniques such as etching, stamping, punching, coining, etc.The semiconductor power module 200 comprises a plurality ofsemiconductor dies 208 mounted on the die pads 204. The semiconductordies 208 may be mounted on the die pads 204 of the substrate 100 by anadhesive, e.g., solder, sinter, glue, etc. In the case that thesemiconductor dies 208 are configured as vertical devices (e.g., asshown) the semiconductor dies 208 may be mounted to provide anelectrical connection between a lower surface 106 terminal (e.g., drain,collector, etc.) of the semiconductor die 208 and the respective die pad206. According to one particular technique, the semiconductor dies 208are soldered by a diffusion soldering technique wherein a very thinlayer of solder material (e.g., less than 30 μm thick) layer is providedand the solder material is reflowed to provide a soldered jointcomprising predominantly intermetallic phases.

The semiconductor dies 208 may be electrically connected to one anotherand/or to other different portions of the semiconductor substrate 100.These electrical connections may be formed using bond wires (as shown),metal clips, ribbons, etc. The semiconductor power module 200additionally comprises an encapsulant body 108 of electricallyinsulating encapsulant material that encapsulates the semiconductor dies208 and associated electrical connections. The encapsulant body 108 cancomprise any of the materials and may be formed according to any of thetechniques as previously described.

According to an embodiment, the semiconductor dies 208 are configured asdiscrete power transistors. A discrete power transistor is a switchingdevice that is rated to accommodate voltages of at least 100 V (volts)and more commonly on the order of 600 V, 1200V or more and/or is ratedto accommodate currents of at least 1 A (amperes) and more commonly onthe order of 10 A, 50 A, 100 A or more. Exemplary device types ofdiscrete power transistors include MOSFETs (Metal Oxide SemiconductorField Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors),and HEMTs (High Electron Mobility Transistors), for example. Moregenerally, the semiconductor dies 208 can have any type of deviceconfiguration, e.g. discrete device configurations such as discretediodes, discrete transistors, discrete JFETs, etc. and integratedcircuit configurations such as logic devices, controllers, drivercircuits, etc. At least some of the semiconductor dies 208 may bevertical devices that are configured to current flowing between a mainsurface and an opposite facing rear surface of the semiconductor die. Atleast some of the semiconductor dies 208 may be lateral devices that areconfigured to current flowing in a direction parallel to main surfaceand an opposite facing rear surface of the semiconductor die.

According to an embodiment, the semiconductor power module 200 isconfigured as a power converter circuit. For example, the semiconductorpower module 200 may be configured as a DC to DC converter, DC to ACconverter, AC to DC converter, etc. These power converter circuits maycomprise one or more half-bridge circuits, wherein a pair ofsemiconductor dies 208 are configured as the high-side switch and thelow-side switch of the half-bridge circuit. Optionally, thesemiconductor power module 200 may comprise additional logic dies thatare configured to control the switching operation of the discrete powertransistor dies which form the half-bridge circuit. Separately or incombination, the power module may comprise additional passive componentsthat are associated with the power conversion circuit, e.g., DC-link,smoothing, etc. For example, as shown, the power module comprises adiscrete capacitor 210 mounted on isolated landing pads 206 of thesubstrate 100.

The semiconductor power module 200 comprises a plurality of thepress-fit connectors 116 secured to the lead frame 202. As shown, thepress-fit connectors 116 may be secured to the die pads 204 or thelanding pads 206. In this case, the die pads 204 or the landing pads 206may correspond to the metal region 102 of the substrate 100 in theprevious description with reference to FIGS. 1-8 . In the case of thepress-fit connectors 116 secured to the die pads 204, these press-fitconnectors 116 may provide an external point of electrical contact to alower surface terminal of the semiconductors dies (e.g., drain,collector) via the die pad 104. In the case of the press-fit connectors116 secured to the landing pads 206, these press-fit connectors 116 mayprovide an external point of electrical contact to an upper surfaceterminal of the semiconductors dies (e.g., source, emitter, gate, etc.)via the landing pad 106.

The semiconductor power module 200 module having the press-fitconnectors 116 secured to the lead frame 202 as shown has notableadvantages over other alternatives. In comparison to a power module thatutilizes a power electronics substrate, e.g., DBC, AMB, IMS, etc. and/orutilizes a custom designed plastic housing, a substantial cost savingsis realized, as the metal processing techniques needed to form the leadframe 202 and press-fit connection are substantially lower. Incomparison to a leaded package design that comprises metal leadsprotruding out from sidewalls of the package body, the press-fit concepteliminates the area required for elongated leads on a lead frame strip,thereby providing better space efficiency and hence lower cost bathprocessing. Moreover, the press-fit concept offers a great deal offlexibility with respect to the location of the package terminals as theentire area of the package is available to arrange the package terminalsinstead of just the package sidewalls, as is the case for a leadedpackage. This can lead to favorable improvements in creepage andclearance, i.e., the shortest distance between exposed conductivesurfaces along an insulating body and through air, respectively.

The semiconductor module of FIG. 9 may comprise additional combinationsof circuit carriers, lead frame structures and/or external connectorsfor further integration. The following exemplary embodiments illustratesome of these variations. In an embodiment, the semiconductor powermodule 200 additionally comprises one ore more PCBs (printed circuitboards) encapsulated within the encapsulant body 108 and spaced apartfrom the lead frame 202. These additional PCBs may accommodate furtherelectronic components such as driver devices, passives, etc. Theseadditional PCBs can be arranged above, below, or laterally spaced apartfrom the lead frame 202. These additional PCBs may comprise separatepress-fit connectors 116 that are attached to the PCBs, e.g., by amechanical connection according to any of the techniques describedherein and/or by a soldered connection. The press-fit connectors 116 mayprotrude out from the encapsulant body 108 in a similar manner as thedepicted press-fit connectors 116 and therefore provide separateelectrical access to the additional PCBs. The size and arrangement ofthese press-fit connectors 116 may be the same or different from thedepicted press-fit connectors 116. Instead of press-fit connectors 116,similar electrical connectors may be connected to the PCS and protrudeout from the encapsulant body 108 so as to provide solderable electricalterminals. These electrical connectors can have a similar or identicalconfiguration as a typical lead structure, e.g., in a surface mountdevice configuration, for example.

Referring to FIG. 10 , a semiconductor power module 200 is depicted,according to another embodiment. In this embodiment, the semiconductorpower module 200 comprises a power electronics substrate 212. The powerelectronics substrate 212 may be a DBC (direct bonded copper) substrate,an AMB (active metal brazed) substrate, or an IMS (insulated metalsubstrate) substrate, for example. The power electronics substrate 100comprises an electrically insulating substrate 214 and a structuredmetallization layer 216 disposed on a electrically insulating substrate100. The electrically insulating substrate 214 can comprise a ceramic orceramic composite and the structured metallization layer 216 can be astructured layer or copper or copper alloy, for example. A semiconductordie 208 such as a power device may mounted on a portion of thestructured metallization layer 216. As shown, the press-fit connectors116 may be secured to portions of the structured metallization layer,wherein these portions correspond to the metal region 102 of thesubstrate 100 in the discussion with reference to FIGS. 1-7 . The powerelectronics substrate 100 may comprise a second metallization layer 218disposed on a rear surface of the electrically insulating substrate 100which may be mated with a heat sink for example. The semiconductor powermodule 200 may optionally comprise a plastic housing 218 and/or maycomprise an encapsulant such as a silicon based potting compoundcovering the power electronics substrate 100.

Referring to FIG. 10 , a semiconductor package 300 is depicted,according to an embodiment. The semiconductor package 300 comprises ametal lead frame 202 with a die pad 204 and one or more landing pads 206spaced apart from the die pad. The metal lead frame 202 can be providedfrom a relatively uniform thickness piece of conductive metal with agenerally planar upper and lower surface 106 is provided, and thefeatures of the substrate 100 (e.g., the die pads 204 and landing pads206) are formed by metal processing techniques such as etching,stamping, punching, coining, etc. A semiconductor die 208, such as apower semiconductor die is mounted on the die pad 204. The semiconductorpackage 300 comprises a metal interconnect clip 220 that provides anelectrical connection between an upper surface terminal of thesemiconductor die 208 and one of the landing pads 206. The semiconductorpackage 300 additionally comprises an encapsulant body 108 ofelectrically insulating encapsulant material that encapsulates thesemiconductor dies 208 and associated electrical connections. Theencapsulant body 108 can comprise any of the materials and may be formedaccording to any of the techniques as previously described. Thesemiconductor package 300 additionally comprises press-fit connectors116 that are secured to the metal interconnect clip, wherein the metalinterconnect clip corresponds to the metal region 102 of the substrate100 in the discussion with reference to FIG. 1 . The press-fitconnectors 116 may eliminate some or all package leads, therebyimproving space efficiency and/or providing advantageous characteristicswith respect to creepage and clearance in a similar manner as previouslydiscussed with reference to the power module of FIG. 9 .

Referring to FIG. 12 , a semiconductor assembly 400 is depicted,according to an embodiment. The semiconductor assembly 400 comprises apair of printed circuit boards 402 with a power device arranged in asandwich configuration between the pair of printed circuits boards 402.The power device comprises a substrate 100 with one or moresemiconductor dies (not shown) mounted thereon. These semiconductor dies208 may be configured as a power conversion circuit, e.g., as previouslydescribed. The pair of printed circuits boards 402 may accommodateadditional devices associated with the power conversion circuit, e.g.,drivers, sensors, measurement circuits, etc. As shown, a passive element404 may additionally be sandwiched between and electrically connected tothe pair of printed circuits boards, for example. This passive element404 may be a DC link capacitor, for example. In this case, the press-fitconnectors 116 extend away from the substrate 100 in both directions.The semiconductor device semiconductor assembly 400 therefore comprisesone of the press-fit connectors 116 extending into each of the twoprinted circuit boards 402 and therefore electrically connected to bothof the printed circuit boards 402. Additional separation elements 406may be interposed between the substrate 100 and the printed circuitsboards. These separation elements 406 may be configured as conductiveheat sinks, e.g., as copper structures. Alternatively, these additionalseparation elements 406 may comprise thermal interface material ifelectrical isolation and thermal conduction is preferred, for example.Alternatively, these additional separation elements 406 may comprise anelectrical insulator such as epoxy material if high electrical isolationis preferred. Alternatively, these additional separation elements 406may be omitted altogether with just a lead frame structure disposedbetween the printed circuit boards 402.

Terms such as “first”, “second”, and the like, are used to describevarious elements, regions, sections, etc. and are also not intended tobe limiting. Like terms refer to like elements throughout thedescription.

As used herein, the terms “having”, “containing”, “including”,“comprising” and the like are open ended terms that indicate thepresence of stated elements or features, but do not preclude additionalelements or features. The articles “a”, “an” and “the” are intended toinclude the plural as well as the singular, unless the context clearlyindicates otherwise.

It is to be understood that the features of the various embodimentsdescribed herein may be combined with each other, unless specificallynoted otherwise.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

1. A method of forming a semiconductor device, the method comprising:providing a substrate that comprises a metal region; forming anencapsulant body of electrically insulating material on an upper surfaceof the metal region; forming an opening in the encapsulant body; andinserting a press-fit connector into the opening; wherein afterinserting the press-fit connector into the opening, the press-fitconnector is securely retained to the substrate and an interfacing endof the press-fit connector is electrically accessible.
 2. The method ofclaim 1, wherein the encapsulant body is formed by a molding processwhereby liquified mold material is formed on the substrate andsubsequently hardened, wherein forming the opening comprises arranging afixed pin over the substrate prior to the molding process, and whereinthe fixed pin prevents the liquified mold material from forming at alocation corresponding to the opening.
 3. The method of claim 2, furthercomprising forming a recess in the upper surface of the metal region,wherein the opening is formed directly over the recess, and wherein theopening is larger than the recess such that the recess is completelyexposed by the opening.
 4. The method of claim 3, wherein the recess hasa first diameter at the upper surface of the metal region, and wherein adiameter of the opening at a lower surface of the encapsulant body thatinterfaces with the upper surface of the metal region is greater thanthe first diameter.
 5. The method of claim 3, wherein the opening istapered such that diameter of the opening gradually increases movingaway from the lower surface of the encapsulant body.
 6. The method ofclaim 5, wherein the recess is formed before forming the encapsulantbody.
 7. The method of claim 5, wherein the recess is formed afterforming the encapsulant body.
 8. The method of claim 3, wherein therecess extends completely through the metal region, and wherein therecess is formed by drilling the upper surface of the metal region andby drilling a rear surface of the metal region that is opposite from theupper surface of the metal region.
 9. The method of claim 3, whereininserting the press-fit connector into the opening comprises insertingthe press-fit connector into the recess, and wherein the press-fitconnector is securely retained to the substrate by compressive forceapplied by the substrate to a base portion of the press-fit connector.10. The method of claim 9, wherein the base portion of the press-fitconnector has a higher material hardness than the metal region.
 11. Themethod of claim 1, further comprising arranging a receptacle in theopening and attaching the receptacle to the substrate, wherein insertingthe press-fit connector into the opening comprises inserting thepress-fit connector into the receptacle, and wherein after inserting thepress-fit connector into the opening the press-fit connector is securelyretained to the substrate via the receptacle.
 12. The method of claim 1,wherein the substrate is an entirely metal structure.
 13. The method ofclaim 1, wherein the substrate is a power electronics substrate thatcomprises an electrically insulating substrate and a structuredmetallization layer disposed thereon, and wherein the metal region is aportion of the structured metallization layer.
 14. A semiconductordevice, comprising: a substrate that comprises a metal region; anencapsulant body of electrically insulating material on an upper surfaceof the metal region; an opening in the encapsulant body; and a press-fitconnector arranged in the opening and securely retained to the substratesuch that an interfacing end of the press-fit connector is electricallyaccessible.
 15. The semiconductor device of claim 14, further comprisinga recess in the upper surface of the metal region, and wherein theopening is directly over the opening and is larger than the recess suchthat the recess is completely exposed by the opening.
 16. Thesemiconductor device of claim 15, wherein the press-fit connector issecurely retained to the substrate by compressive force applied by thesubstrate to a base portion of the press-fit connector.
 17. Thesemiconductor device of claim 16, wherein the press-fit connectorcomprises K88 copper alloy, and wherein the metal region comprises ametal with a lower material hardness than K88 copper alloy.
 18. Thesemiconductor device of claim 14, further comprising one or more powersemiconductor devices mounted on the substrate and encapsulated by themolded body, and wherein the press-fit connector provides a point ofelectrical contact to a terminal of the one or more power semiconductordevices via the metal region.
 19. The semiconductor device of claim 19,wherein the semiconductor device is a power semiconductor module thatcomprises a power converter circuit.
 20. The semiconductor device ofclaim 19, wherein the substrate is arranged between two printed circuitboards, and wherein the semiconductor device comprises one of thepress-fit connectors extending into each of the two printed circuitboards.